Apparatus for dewaxing oils



INVENTORS R. E. BURK ET Al.

`APPARATUS FOR DEWAXING OILS Filed July 1. 1955 S QQ June 2l, 1938.

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Patented June 2l, 1938 anse 2,121,420 APPARATUS Fon DEWAXING OILS Robert E. BurkandEverett C. Hughes, Cleveland, Ohio, assignors to TheStandard `Oil Company (Ohio), Cleveland, Ohio, a corporation of Ohio Application July 1, 1935, serial N0. 29,254

5 Claims.

This invention relates to apparatus for removing wax from mineral oils and the like; and it is'among the objects of the invention to provide means for `separating the wax in a continuous manner as opposed to the prevalent intermittent or batch-wise type of operation'where a lter press has to be loaded up and then dis# charged of its Wax cakes. Other objects and advantages will appear as the description 'proceeds. y

"'To the accomplishment of the foregoing'and related ends,`the invention, then, comprises the means hereinafter fully described, and particularly pointed out in the claims, the following description vand the annexed drawing `setting forth in detail certain illustrative embodiments of the invention, these being indicative however, of but a few of the various ways in which the principle of the invention may be employed.

In said annexed drawing f Fig. lisa semi-diagrammatic vertical sectional view of apparatus contemplated; and Fig. 2 is an enlarged detail, partly broken away.

Referring more particularly to the drawing,

there isjshown a porous diaphragm chamber 2 arranged with both ends in communication with a tank 4 through connections 5, 6, a circulating pump 3' being interposed. Surrounding the diaphragm chamber 2 is a housing 'l which has connections AIl from its upper end and 8'. from its lower end to an oil-receiving tank 9. The construction of thevdiaphragm member 2 may vary somewhat in detail, it involving Vin general Aa porous wall through which oil may permeate readily,` while passage of wax flakes and the like is prevented. 0n account of the fluid current through the fair-way of the diaphragm chamber, and to an extent also on account of relatively slight differential of pressure between the inside of the diaphragm and its outside, there is but slight tendency for wax akes in suspension to pile up on the diaphragm surface. Rather, the wax circulates as a crystal slurry past the diaphragm chamber, while the oil may pass out the pervious wall into the housing l and thence to the tank 9. By admixing with the wax-containing oil, solvents of suitable character, as mentioned more in detail below,` the wax slurry may be progressively concentrated in its circulatory cycle, while the oil is progressively passed on out to the receiving tank. With a suitably large housing anduse ofproperly separable solvents,` separation goes on'in the housing and the oillayer may be quietly drawn off 'from thev top of the tank 9 by pipe."

Connected to thetank 4 by connections Ill, I3, including a suitable forwarding means or pump I4, are supply tanks I5, I6. In these, the wax-containing oil which is to be treated, may bebrought in readiness for introduction to the (Cl. 196--19l circulating cycle 4, 2, and where using solvents with the oil, the mixtures of wax-containing oil and solvent may be Ithus properly prepared and chilled with such tank facilities so as to be fed as needed to the circulating cycle d, 2. A by-pass With a control valve 20 may be arranged across the chamber 2 if desired, available for emergency or special usage, but normally the valve 2Q is shut. Another convenience-connection guarded by a valve 2|, which is ordinarily shut, provides any desired communication across the bottom of the system. With valves 20 and 2| closed and valve 22 open, the regular circulating cycle is such as to pass the mixture of oil and solvent and wax continuously through accumulating tank 4 and permeable Walled pass-way 2, the oil and solvent escaping through vthe permeable wall 2 into the surrounding housing l. As thus readily understood, the slurry of chilled wax suspension tends to concentrate progressively, and feed liquid is supplied through pipe I0 as needed. Conveniently, a float-valve 35 controls such feed, the float-valve being of any desired mechanical or electrical-intermediary detail. The wax-containing oil to be treated is introduced into the system through connections 26, and such oils may be for -may replace the benzene in the mixtures of benzene, or a solvent may be chosen which has high solvent power for oil and low solvent power for wax in an -appropriate temperature range, as ethylene chloride, methylene chloride, etc. Such solvent may be introduced along with the oil, having been previously mixed at some convenient point, or the solvent may be introduced through connection 2l, the valve 28 being closed. Desirably, the tanks I5, I6, are in a refrigerating room, or are provided with refrigerating means, and by appropriatemanipulation of the valves, either tank may be put in communication with the accumulator 4 through pipe I ll, The pump I 4 may also `be employed as an agitatng means, suitable opening of the valve 29, 29 allowing recycling of liquid back and around through the tanks l5, I6, as desired' at any time, in order to keep the wax crystals as precipitated out, in

free suspension. Where desired, further means for keeping the slow-motion plunger pump 3I, may be controlled to provide a stroke every minute or at longer intervals to produce back-flow, and this operation may be made automatic. For air blow-back, valve 32 is closed and air-valve 33 is opened, allowing high pressure air from source 30 to pass into the housing 1 and against vand through the diaphragm 2. By opening the valve 34 at the top of accumulator tank 4, free exit of air ow suilicient for the purpose may be had. The housing 1 may be preliminarily emptied of liquid by opening the valve in pipe 8.

While canvas may be employed, filter-surfaces of more permanent character than textiles are preferable, such as porous elements of the commercial material known as alundum, ceramic material, metal, etc. The particular shape of the lter unit 2 may of course vary in accordance with circumstances, and while tubular, that is, of hollow section, it may be round, rectangular or polygonal, and where desired there may be framing elements or rib-beams 2c extending at opposite sides, or in more frequent positioning, between the heads 23, .as relatively thick frame pieces of ceramic with thin porous ceramic plates therebetween, or the frame elements may be of metal with ceramic or metal porous plates between. The respective heads communicate with the conduits 5, 6, these entering through lthe walls of the housing 1 in suitably oil-tight relation. In accordance with Poisseules law of viscous flow in capillary passages,

U being the velocity of flow, p the pressure drop through the capillary, d the inside diameter of the capillary pass-way, l its length, and m the absolute viscosity of the liquid. It -thus follows that the rate of passage of liquid through a capillary pass-way .is inversely proportional to its length, and in accordance with the present invention capillary lter plates of ithin Yceramic or metal are particularly advantageous. Porous metal diaphragms may be prepared by removing one component of a eutectic alloy :from a suitably thin cast diaphragm, for instance :a copper-lead alloy, by suitable melting out of the low melting constituent, or the diaphragm may be prepared by spray-deposition of molten metal or by partially closing the pores of a nely punched plateV by electroplating. Reinforcement is thus possible in such metal structures, and I may employ a wire mesh reinforce layer 12b, upon which and in the interstices of which is deposited the iiltering portion of metal of alloy or :sprayed metal as just noted, such deposited metal forming layers 2a on the reinforce 2b. The latter may be of woven steel wire of medium mesh, or in some instances of brass wire. The porous filter elements may be clamped to the inlet and outlet heads 23 of the filter compartment by suitable means, for instance clamps 24, tightened in yplace by bolts or the like 25.

By the provision of two or more tanks fI5, I6, relay use of each in turn for preparation-of any desired mixture of oil and solvent liquid is facilitated, for the supply to Vthercirculating system 4, 2, and any requisite amount of pre-cooling is readily attained. Each tank may with .advantage also have an agitator A and driving motor M.

If a solvent which is Vheavier than Wax is lemployed inconjunction with the oil, such for instance as a solvent made up of benzene and liquid sulphur dioxide, advantage of the gravitational relations may best be had by circulating the liquid in the -cycle 4, 2, in the direction of first the connection 5 to the diaphragm chamber 2, and thence back through connection 6 to the accumulator 4. The by-pass valve 20 is of course closed, likewise valve 2|, and valve 22 is open. If a solvent which is lighter than wax be employed, for instance propane, hexane, etc., the direction of the iiuid circuit will more advantageously be the reverse. With the connection 5 placed well above the bottom of the accumulator 4, disturbance of wax settlings in the accumulator will be a minimum. A draw-off line I I controlled by valve I2 permits nal removal from the system. The size of the accumulator4 may advantageously be such that it will hold a days production of wax from the plant, and thus while in continuouscirculation the wax concentrates and accumulates in this portion of the system, 4, 2, and the accumulation of wax in tank 4 needs be taken off merely once for each days cycle.

As a further feature, the accumulator 4 may have a connection controlled by a Valve 4I, to another chamber 43 andlter 44, preferably a mixer and chiller chamberv being interposed between the chambers 4 and 43. The mixer 45 may also ldesirably be provided with a motor driven agitating means 46. Surrounding the iilter element 44 is a housing 41, and outlet pipes 48, 49 therefrom at the top and bottom lead to a suitable receiver. The iilter 44 is in a circuit with chamber 43 by means of suitable connections 50, 5I, analogously to the circulation cycle for elements 2 and 4, and a by-pass 52 and control valves 53, 54 may be provided. With the chamber 45 in connection with the chamber or accumulator 43 there may be a suitable forwarding means or pump 55. With this arrangement, the wax concentrate may be drawn olf from the bottom of accumulator `4, valve 4I being opened and valve I2 closed, to the mixing chamber 45, where washing solvent for the wax may be supplied through valve controlled connection 56 from some suitable source of supply. The wax concentrate and solvent may be agitated here, and at a suitably reduced temperature be forwarded to the chamber 43, and thence be circulated by the circulating vmeans or pump 51 around the circuit including filter passage 44 and accumulator 43, and connections and 5I. Again, the liquid passes out through capillary filter 44 whose structure may be as detailed above in connection with the description of filter 2. The liquid here is solvent with such trace of oil as is washed out of the wax. This may be taken off to a storage tank by connection 48, or preferably may be returned through valve controlled connection 60 to the inlet 21 of the initial charging side of the wax separator system. The wax slurry concentrate thus washed, and accumulating in the accumulator 43 may finally be drawn off by valve controlled connection 6 I and the solvent be eliminated from the wax.

Other modes of applying the principle of the invention may be employed, change being made as regards the details described, provided however, the features stated in any of -the following claims, or the equivalent of such, be employed.

We therefore particularly lpoint out and distinctly claim as our inventionz l. Dewaxing apparatus, which comprises a stationary channel Ymember with Vunobstructed lumen and a porous wall, frame elements for the latter, support heads and clamps for holding the wall to the heads, an accumulator tank, upper and lower connections from said tank to the ends of said channel member for circulating a wax slurry suspension therethrough, a plurality of supply tanks, connection means for communicating either thereof with the accumulator tank,

agitating means for said supply tanks, means` for refrigerating said supply tanks, means for introducing oil into said tanks, means for introducing a solvent in said tanks, a float valve controlling the feedof said connection means into said accumulator tank, a housing spaced about said channel member, a receiving tank, connections from the upper and lower ends of said housing to said receiving tank, means for applying back duid-pressure in said housing including an air suppl;7 to said housing, and a pump in the upper connection to said receiving tank, and a by-pass around the said pump, another tank connected with the bottom of said accumulator tank, another accumulator tank connected with said last-named tank, agitating means for said last named tank, and means for Washing accumulated wax including a channel member with unobstructed lumen and porous wall, upper and lower connections from said last accumulator tank to the ends of said last channel member for circulating the wax slurry suspension therethrough, a housing spaced about said last channel member, a connection for drawing 01T liquid from said housing, and connections for returning liquid from said housing to said first-named accumulator tank and its supply tanks.

2.v Dewaxing apparatus, which comprises a stationary channel member With unobstructed lumen and a porous wall, frame elements for the latter, support heads and clamps for holding the wall to the heads, an accumulator tank, upper and lower connections from said tank to the ends of said channel member for circulating a wax slurry suspension therethrough, a plurality of supply tanks, connection means for communicating either thereof with the accumulator tank, agitating means for said supply tanks, means for refrigerating said supply tanks, means for introducing oil into said tanks, means for introducing a solvent in said tanks, a float valve controlling the feed `of said connection means into said accumulator tank, a housing spaced about said channel member, a receiving tank, connections from the upper and lower ends of said housing to said receiving tank, means for applying back duid-pressure in said housing including an air supply to said housing, and a pump in the connection to said receiving tank, and a by-pass around the said pump, an-

` other tank connected with the bottom of said accumulator tank, another accumulator tank connected with said last-named tank, agitating means for said last named tank, and means for Washing accumulated wax including a channel member with unobstructed lumen and porous wall, upper and lower connections from said the latter, support heads and clamps for holding the Wall to the heads, an accumulator tank, upper and lower connections from said tank to said channel member for circulating a Wax slurry suspension therethrough, a plurality of supply tanks, connection means for communicating either thereof with the accumulator tank, agitating means for said supply tanks, means for refrigerating said supply tanks, means for introducing oil into said tanks, means for introducing a solvent in said tanks, a float valve controlling the feed of said connection means into said accumulator tank, a housing spaced about said channel member, a receiving tank, connections from the upper and lower ends of said housing to said receiving tank, means for applying back fluid-pressure in Vsaid housing, another tank connected with said accumulator tank, and means for washing accumulated wax, including la porous-wall channel member and a housing spaced about said last channel member, a connection fromV said other tank to said porous- Wall channel member, and a connection for Withdrawing liquid from said housing.

4. Dewaxing apparatus, which comprises a stationary channel member with unobstructed lumen and a porous wall, an accumulator tank, upper and lower connections between said accumulator tank and said channel member for circulating oil through said channel member and said accumulator tank, means communicating to the accumulator tank for chilling the oil, another tank for washing accumulated wax, a connection from said accumulator tank to said washing tank, a housing spaced about said channel member, and a connection from said accumulator tank to said washing means, a connection for withdrawing liquid from said housing.

5. Dewaxing apparatus, which comprises a stationaryV channel member with unobstructed lumen and a porous wall, frame elements for the latter, support heads and clamps for holding the wall to the heads, an accumulator tank,

`upper and lower connections from said tank tothe ends of said channel member for circulating a Wax slurry suspension therethrough, supply tank means in communication with said accumulator tank, agitating means for said supply tank means, means for refrigerating said supply tank means, a oat valve controlling the feed from said supply tank means into said accumulator tank, a housing spaced about said channel member, a receiving tank, connections from the upper and lower ends of said housing to said receiving tank, means-for Vapplying back huid-pressure in said housing, including a pump in the connection to said receiving tank, and a by-pass around said pump, another tank connected to the bottom of said accumulator tank, another accumulator tank connected with said last-named tank, and means for washing accumulated wax, includinga hollow channel member with porous wall, upper and lower connections from said last accumulator tank to the ends of said last channel member for circulating wax slurry suspension therethrough, a housing spaced about said last channel member, and a connection for withdrawing liquid from said housing.

ROBERT E. BURK. EVERETT C. HUGHES. 

